Binary-medium constitutive model for frozen soils based on CT dynamic scanning

It is of great significance to carry out experimental researches on the macro-meso-mechanical properties of frozen soils to reveal the mechanism and the relationship between the meso- and the macro-meso-mechanical properties of frozen soils. The triaxial compression tests on the saturated frozen soils under four temperatures and four confining pressures are carried out by using the newly developed frozen soil triaxial instrument, which can cooperate with medical CT for dynamic scanning. A total of 8 CT dynamic scans are performed on the samples during the axial loading process. Through the statistical analysis of CT numbers and stress-strain curves, it is found that when the stress-strain curve is strain hardening, the average CT number of the frozen soil samples decreases linearly with the increase of the axial strain. When the stress-strain curve is strain softening, the average CT number of the frozen soil samples decreases rapidly at the softening stage. Based on the evolution laws of the average CT number of samples during the process of dynamic scanning, the breakage rate is characterized by the average CT number value, and the mesoscopic constitutive model for the saturated frozen soils is established, and the established constitutive model is verified through the test data. The results show that the proposed constitutive model can well predict the stress-strain behavior of frozen soils under the conventional triaxial stress path.